Satellite-tracked Turtles Survive Hurricane Isabel

James Owen in Englandfor National Geographic News

September 25, 2003

Shellby had been reported missing, presumed dead, after Hurricane Isabel struck the eastern U.S. coast last week. Feared washed up or drowned, she is one of 11 female sea turtles being tracked by researchers keen to discover where they go after laying their eggs on land.

But Shellby, a loggerhead turtle, survived the storm. Having been fitted with a satellite transmitter while on Bald Head Island in North Carolina, her signals have since been picked up again near Virginia Beach.

The story of Shellby's voyage, plus those of ten other tagged turtles, have captivated a worldwide audience, with Internet users able to chart their daily progress towards far-off feeding grounds by logging on to Seaturtle.org.

The nonprofit organization provides instant access to pioneering research into sea turtle migrations in the Caribbean and western Atlantic. Based in the U.S., Seaturtle.org is run by various groups dedicated to conserving these endangered marine reptiles. They include UK scientists who are tracking 11 green and loggerhead turtles using the latest satellite technology.

Brendan Godley, a marine biologist with the Marine Turtle Research Group based in Exeter, England, says the project has two main aims: to find out where the animals live when they are not breeding, and to understand why and how they migrate over vast distances.

He added: "If we don't know where these animals go, how can we conserve them? But if we can find out, then a mosaic of protected areas can be created to encompass a large part of their lifecycle.

"We also want to know what drives their migration patterns. For instance, as the seas get colder in winter, are they going to hit the bottom and undertake a type of hibernation, as they do in the Mediterranean, or will they head south?"

Egg-laying

The turtles had satellite transmitters fitted to their shells this summer while laying eggs on beaches in North Carolina, South Carolina, and the Cayman Islands in the Caribbean.

The four North Carolina turtles headed north, straight into the path of Hurricane Isabel, which recently brought chaos and devastation to the eastern seaboard. Researchers feared the worst, especially when one of them, named Shellby, stopped sending signals.

But Matthew Godfrey, biologist for the North Carolina Sea Turtle Project, says all four turtles are now transmitting again, adding: "One thing to keep in mind is that increased wave action and higher swells associated with storms can result in fewer transmissions." This is because the transmitters switch on only when fully exposed as the turtles come up for air.

Godfrey suspects adult turtles are good at dealing with violent seas, but says a bigger problem associated with the hurricane came from heightened sea levels and crashing waves which destroyed many thousands of unhatched eggs.

He says the tagged turtles have already provided important information since leaving their breeding beaches. "We've learned that they don't go directly south at the end of the nesting season, rather they all turned north to Chesapeake Bay or beyond," he added. "Their presence in inshore waters of the mid-Atlantic states highlights the importance of these zones as feeding areas."

The turtles migrating from the Cayman Islands to foraging grounds off Central and South America have also surprised scientists by their speed of travel.

Brendan Godley said: "Myles, who is migrating at the moment, has just reached Mexico's Yucatán Peninsula. She swam due west, covering some 700 kilometers (435 miles) in a weekthat's 100 kilometers (about 60 miles) a day which is pretty good going. And as she's a green turtle, living mainly off sea grasses and algae, she wouldn't have eaten a bite during the crossing."

Island Exploitation

Myles is one of just a few dozen sea turtles that still nest on the Caymans. When Christopher Columbus discovered the islands in 1503, he named them "Las Tortugas"the Turtles. Green turtle numbers back then were estimated at over 6.5 million. The species later became central to the region's economy and culture. Their historical importance is still evident today, with green turtles featured on the islands' coat of arms and dollar bills. But by the 19th century commercial overexploitation had almost wiped them out.

This is mirrored in the collapse of turtle populations throughout the world. Conservationists identify habitat degradation due to coastal development, pollution, and exposure to toxins, accidental capture by fishermen, and collisions with commercial vessels and personal watercraft as being among the main modern-day threats to the animals.

Both the green turtle, which can weigh up to 205 kilograms (452 pounds), and the loggerhead turtle are now classified as endangered by the International Union for the Conservation of Nature.

Researchers hope information gleaned from the satellite tracking project will help them conserve remaining populations.

For instance, Matthew Godfrey says The North Carolina Sea Turtle Project will now compare migratory routes taken by the Bald Head Island loggerheads with commercial fisheries in the region with a view to suggesting management measures to prevent harmful interactions.

In the meantime, turtle lovers everywhere can log on to the Web and find out just where Shellby and her fellow travelers are headed (see link at the bottom of this page).